The Double Authentication Proxy is a connector that will let you use mutual TLS (TLS/SSL client certificates) for build node authentication.
This results in a two-fold authentication strategy:
- CI User: a project-specific token must be presented to submit a signing request (usually stored as a secret in the CI system’s project configuration)
- Build node: only specific build nodes are able to submit the signing request
You may configure the system to accept certificates based on
- subject/distinguished name conditions (e.g. common name or organizational unit)
- the issuer (e.g. issued by a certain immediate certificate)
- a Microsoft Certificate Server template ID (see below)
Use Active Directory computer groups via Microsoft Certificate Server
This is a very straightforward way to authorize specific groups of build nodes for SignPath:
- Include all build nodes with certain security properties in a computer group
- Use Microsoft Certificate Server to assign computer certificates to this group (we recommend using short-lived certificates, i.e. days or weeks, for security critical groups)
- Specify the template ID in the Double Authentication Proxy configuration
- Register the Double Authentication Proxy as trusted build system (see configuration)
- Submit signing requests using mTLS, e.g. using the PowerShell cmdlet. Use the template ID to select the correct certificate client certificate.
This diagram shows how machine certificates, Double Authentication Proxy and SignPath work together:
Contact our support team for installable container images and documentation.